ABSTRACT
The circulatory system provides the means of transport for essentially everything in an animal's body. Because control of the rate of blood flow and its distribution in a fish is based primarily on homeostasis of respiratory gases, the cardiovascular responses to pollution are included in this chapter with the respiratory system. The typical teleost fish respiratory system consists of the buccal and paired opercular cavities and the gills suspended between them. A cough occurs at a random position during a respiratory cycle and is characterized as a rapid expansion and contraction of the buccal and opercular cavities. These movements produce a two-to fivefold increase in the reversal phase of the differential pressure across the gills. The function of the circulatory system is intimately related to the process of respiratory gas exchange and the control mechanisms for this system are largely based on the detection of changes in blood oxygen.
